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  1. /*
  2.  * Copyright (c) 2001-2004 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup time
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file
  35.  * @brief   High-level clock interrupt handler.
  36.  *
  37.  * This file contains the clock() function which is the source
  38.  * of preemption. It is also responsible for executing expired
  39.  * timeouts.
  40.  */
  41.  
  42. #include <time/clock.h>
  43. #include <time/timeout.h>
  44. #include <config.h>
  45. #include <synch/spinlock.h>
  46. #include <synch/waitq.h>
  47. #include <func.h>
  48. #include <proc/scheduler.h>
  49. #include <cpu.h>
  50. #include <arch.h>
  51. #include <adt/list.h>
  52. #include <atomic.h>
  53. #include <proc/thread.h>
  54. #include <sysinfo/sysinfo.h>
  55. #include <arch/barrier.h>
  56. #include <arch/interrupt.h>
  57. #include <mm/frame.h>
  58. #include <ddi/ddi.h>
  59. #include <udebug/udebug.h>
  60.  
  61. /* Pointer to variable with uptime */
  62. uptime_t *uptime;
  63.  
  64. /** Physical memory area of the real time clock */
  65. static parea_t clock_parea;
  66.  
  67. /* Variable holding fragment of second, so that we would update
  68.  * seconds correctly
  69.  */
  70. static unative_t secfrag = 0;
  71.  
  72. /** Initialize realtime clock counter
  73.  *
  74.  * The applications (and sometimes kernel) need to access accurate
  75.  * information about realtime data. We allocate 1 page with these
  76.  * data and update it periodically.
  77.  */
  78. void clock_counter_init(void)
  79. {
  80.     void *faddr;
  81.  
  82.     faddr = frame_alloc(ONE_FRAME, FRAME_ATOMIC);
  83.     if (!faddr)
  84.         panic("Cannot allocate page for clock");
  85.    
  86.     uptime = (uptime_t *) PA2KA(faddr);
  87.    
  88.     uptime->seconds1 = 0;
  89.     uptime->seconds2 = 0;
  90.     uptime->useconds = 0;
  91.  
  92.     clock_parea.pbase = (uintptr_t) faddr;
  93.     clock_parea.vbase = (uintptr_t) uptime;
  94.     clock_parea.frames = 1;
  95.     clock_parea.cacheable = true;
  96.     ddi_parea_register(&clock_parea);
  97.  
  98.     /*
  99.      * Prepare information for the userspace so that it can successfully
  100.      * physmem_map() the clock_parea.
  101.      */
  102.     sysinfo_set_item_val("clock.cacheable", NULL, (unative_t) true);
  103.     sysinfo_set_item_val("clock.faddr", NULL, (unative_t) faddr);
  104. }
  105.  
  106.  
  107. /** Update public counters
  108.  *
  109.  * Update it only on first processor
  110.  * TODO: Do we really need so many write barriers?
  111.  */
  112. static void clock_update_counters(void)
  113. {
  114.     if (CPU->id == 0) {
  115.         secfrag += 1000000 / HZ;
  116.         if (secfrag >= 1000000) {
  117.             secfrag -= 1000000;
  118.             uptime->seconds1++;
  119.             write_barrier();
  120.             uptime->useconds = secfrag;
  121.             write_barrier();
  122.             uptime->seconds2 = uptime->seconds1;
  123.         } else
  124.             uptime->useconds += 1000000 / HZ;
  125.     }
  126. }
  127.  
  128. /** Clock routine
  129.  *
  130.  * Clock routine executed from clock interrupt handler
  131.  * (assuming interrupts_disable()'d). Runs expired timeouts
  132.  * and preemptive scheduling.
  133.  *
  134.  */
  135. void clock(void)
  136. {
  137.     link_t *l;
  138.     timeout_t *h;
  139.     timeout_handler_t f;
  140.     void *arg;
  141.     count_t missed_clock_ticks = CPU->missed_clock_ticks;
  142.     unsigned int i;
  143.  
  144.     /*
  145.      * To avoid lock ordering problems,
  146.      * run all expired timeouts as you visit them.
  147.      */
  148.     for (i = 0; i <= missed_clock_ticks; i++) {
  149.         clock_update_counters();
  150.         spinlock_lock(&CPU->timeoutlock);
  151.         while ((l = CPU->timeout_active_head.next) != &CPU->timeout_active_head) {
  152.             h = list_get_instance(l, timeout_t, link);
  153.             spinlock_lock(&h->lock);
  154.             if (h->ticks-- != 0) {
  155.                 spinlock_unlock(&h->lock);
  156.                 break;
  157.             }
  158.             list_remove(l);
  159.             f = h->handler;
  160.             arg = h->arg;
  161.             timeout_reinitialize(h);
  162.             spinlock_unlock(&h->lock); 
  163.             spinlock_unlock(&CPU->timeoutlock);
  164.  
  165.             f(arg);
  166.  
  167.             spinlock_lock(&CPU->timeoutlock);
  168.         }
  169.         spinlock_unlock(&CPU->timeoutlock);
  170.     }
  171.     CPU->missed_clock_ticks = 0;
  172.  
  173.     /*
  174.      * Do CPU usage accounting and find out whether to preempt THREAD.
  175.      */
  176.  
  177.     if (THREAD) {
  178.         uint64_t ticks;
  179.        
  180.         spinlock_lock(&CPU->lock);
  181.         CPU->needs_relink += 1 + missed_clock_ticks;
  182.         spinlock_unlock(&CPU->lock);   
  183.    
  184.         spinlock_lock(&THREAD->lock);
  185.         if ((ticks = THREAD->ticks)) {
  186.             if (ticks >= 1 + missed_clock_ticks)
  187.                 THREAD->ticks -= 1 + missed_clock_ticks;
  188.             else
  189.                 THREAD->ticks = 0;
  190.         }
  191.         spinlock_unlock(&THREAD->lock);
  192.        
  193.         if (!ticks && !PREEMPTION_DISABLED) {
  194. #ifdef CONFIG_UDEBUG
  195.             istate_t *istate;
  196. #endif
  197.             scheduler();
  198.  
  199. #ifdef CONFIG_UDEBUG
  200.             /*
  201.              * Give udebug chance to stop the thread
  202.              * before it begins executing userspace code.
  203.              */
  204.             istate = THREAD->udebug.uspace_state;
  205.             if (istate && istate_from_uspace(istate))
  206.                 udebug_before_thread_runs();
  207. #endif
  208.         }
  209.     }
  210.  
  211. }
  212.  
  213. /** @}
  214.  */
  215.